The present invention relates to a system for storing and retrieving information bearing units or modules, and in particular to a special purpose retrieval system which provides automatic random access of a larger number of items stored in a fixed area.
There are many types and kinds of information retrieval systems presently available, each having its own advantages and disadvantages. For example, large scale computer based information retrieval systems are well known in the art (see U.S. Pat. No. 3,405,457). However, they require expensive high speed mass storage devices such as disk packs and relatively sophisticated central processes as controllers.
A number of random access retrieval mechanisms exist which bring together a processing station with a stored item, usually by moving the stored items. Many such devices use a rotating one-dimensional array of stored items (for example, slides, U.S. Pat. No. 3,510,215; microfiche, U.S. Pat. No. 3,704,451; or tape cassettes, U.S. Pat. No. 3,484,055); however, when a large number of items are to be stored, a two dimensional storage area is required. Such mechanisms use either a storage array capable of movement in two directions (U.S. Pat. No. 3,243,780) or an array moving in one dimension with moving selection mechanism (U.S. Pat. No. 3,164,059) or moving processing station (U.S. Pat. No. 2,918,656). These devices have the disadvantage of requiring considerable power to accelerate a large storage array and/or processing station, and to decelerate into a precise position required for processing. One device which attempts to overcome power requirements utilizes a continuously rotating array of items (U.S. Pat. No. 3,378,827). However, the storage array is restricted to one dimension and requires specially designed items. Another disadvantage of these devices is mechanical complexity and associated high cost.
Inexpensive random access tape cassette players exist for the home entertainment market (U.S. Pat. Nos. 3,524,949 and 3,682,483) but the number of cassettes these devices will accommodate is exceedingly limited (about 20 maximum) and preselection capabilities are extremely limited.
Electronic control of automated selection mechanisms is seen in devices related to audio entertainment such as juke boxes. Controllers incorporating memory to store selections are known (U.S. Pat. Nos. 3,511,351; 3,555,509 and 3,739,342) as well as controllers which allow multiple program options (3,541,514). Such systems, however, have limited storage capabilities and accommodate only storage of single addresses, i.e. there is no secondary addressing within an information unit.